The art of preparing low-calorie butter substitutes and margarine-like spreads has focused on the removal of fat since fat (in both solid and liquid form, i.e., fats and oils) comprises a major amount of the weight of these products--typically about 80 to about 85% by weight.
Dietary fat is high in calories. It is the most concentrated source of energy of all the nutrients, supplying 9 kcal/gram, about double that contributed by either carbohydrate or protein. The amount of fat in the American diet has increased in the last 60 years by about 25% (Mead, J., et al., Lipids, Plenum, New York, 1986, page 459; this and other references cited hereafter are hereby incorporated herein by reference), so that fats now provide approximately 34% (or more, by some estimates) of the daily caloric intake.
Because fats are high in calories and because some fats have been associated with health risks when consumed in large quantities over time, a number of national advisory committees on nutrition have recommended that the total amount of fat in the diet be reduced significantly (Gottenbos, J.J., chapter 8 in Beare-Rogers, J., ed., Dietary Fat Requirements in Health and Development, A.O.C.S. 1988, page 109).
The fat component of butter substitutes has been reduced in a variety of ways--in each case adding something to compensate for the weight and volume of the fat eliminated. This has been achieved with various degrees of success by emulsifying with more water, using gelling or thickening agents to bind added water, adding discrete small particles which give the sensation of fat in the mouth, and using synthetic fats to replace the natural ones.
The use of synthetic fats is often more expensive than is justified commercially. Moreover, fat replacements which are based on wholly non-digestible oily materials, such as sucrose polyesters (see, for example Mattson, et al., U.S. Pat. No. 3,600,186), have a tendency to pass through the digestive tract intact. Unless something is done to physically bind them to other food components, they are excreted in essentially the form in which they are introduced. The liquid products of this type have been known to be the subjects of frank anal discharge. The preparation of liquid butter substitutes using products of this type has complications beyond mere cost.
Emulsions that use more water and less fat, essentially stretch the fat structure of the water-in-oil emulsions. This technique, by decreasing the amount of fat available to enclose the water, has stability limits. Moreover, the water tends to release from the emulsion when the fat melts, and it tends to undesirably wet starch-based substrates such as bread, muffins, cakes and crackers. When used as a topping on vegetables, the melted phase has poor cling, and water and other ingredients tend to pool under the food to which the topping is applied, thus not providing the desired flavor and appearance for the consumer.
Other patent disclosures suggest using a gelling agent such as gelatin or agar (see, for example, U.S. Pat. No. 4,103,800, to Bodor, et al.) or maltodextrin (e.g., U.S. Pat. No. 4,917,915, to Cain, et al.) to thicken the water phases in these water-in-oil emulsions and prevent them from flowing until melt occurs in the mouth. However, melting on hot toast or the like will also release the water and make the toast soggy. Also the gelling agents add a paste-like taste to the product. If the amount of gelling agents is increased sufficiently to overcome the melting problem, then the pasty impression of the product is increased.
In the case of oil-in-water emulsions, Bosco and Sledzieski, disclosed in U.S. Pat. No. 4,468,408, that a liquid spread could be made having less than 30% fat. They taught the use of a combination of an emulsion stabilizer and an emulsifier system which included both a lipophilic and a hydrophilic emulsifier. The emulsion stabilizer could be a gelling gum, but at a level below the amount needed to gel all of the liquid.
Recently, a number of techniques have been proposed for creating dispersions of gelled or coagulated materials to simulate a fat emulsion or cream. Among these are U.S. Pat. No. 4,828,396, to Singer, et al., wherein the use of spheroidal particles of less than two microns was asserted to have a fatty character. Similarly, in U.S. Pat. No. 5,338,561, to Campbell, et al, it is disclosed that gelling carbohydrates can be sheared into fine particles during gelling to provide a thermally reversible gel exhibiting a fat-like mouth feel. Campbell, et al., farther indicate that thickeners can be added to the resulting cream in some embodiments, but it is not required as the first phase is thin due to the shearing step. Because the gel is thermally reversible, however, it loses its water on heating, so the emulsions are disclosed as useful for non-dairy creams, dressings, mayonnaises and the like, and not products applied to hot substrates. Moreover, the product must be packed at low temperatures under aseptic processing conditions. In addition, applications of this type of product under conditions where thermal cycling occurs have resulted in an undesirable consistency due to melting and regelling. This problem is also encountered during product distribution and storage if warming occurs.
In U.S. Pat. No. 5,324,531, Hoefler, et al., prepare a fat-simulating composition composed of shredded and hydrated carbohydrate gel particles that are elongated and irregularly-shaped and of a certain size, with the longest axial dimension of up to about 250 microns and a mean volume diameter of from about 10 to about 100 microns. The product, currently marketed under the tradename Slendid.RTM., is prepared by mixing a carbohydrate with water to form a gel and then chopping and shearing the gel into particles. In order for the gel particles to stay unchanged on storage, the water activities of the carbohydrate making up the gel paticles and the water phase of the food product in which the particles are a component have to be comparable. Alone, the product has a paste-like consistency and taste with no melting or flow in the mouth, and gels made with the composition will weep water on long-term storage unless special precautions are taken. If prepared at lower concentrations to avoid the paste-like consistency, the product's viscosity is too thin, resulting in a product that looks like slime.
U.S. Pat. No. 5,082,684 to Fung and U.S. Pat. No. 5,158,798 to Fung, et al., disclose fat substitutes formed by adding a gel-forming composition to an aqueous phase to form a non-pourable water phase, which is then added to an oil phase to form a product that is pourable.
Fat mimetics based on carbohydrates and proteins are advantageous because they have less than half the caloric density of typical triglyceride margarine fats and are employed at less than a one-to-one basis (due to water of hydration). Fat is not, however, without benefits unique to itself, and desirable low-fat spreads retain these. Fat contributes--sometimes greatly--to the palatability and flavor of food, since most food flavors are fat-soluble. Fat is also important as a carrier of the fat-soluble vitamins, A, D, E, and K. Water-soluble flavors and salt tend to concentrate in the aqueous phase and it is typical to also retain an aqueous phase which provides good release of these components. As the water phase is only 20% in margarine, the high concentration of flavor and salt in that phase provides a pleasing mouth sensation. In lower fat products, the water phase is diluted, and flavor benefit is lost. Whenever an aqueous phase is employed, it is necessary to provide a preservative to protect against microbiological growth and spoilage.
Despite the development of a wide variety of fat substitutes and butter replacements taught by the art and available on the market, there remains a need for a liquid butter replacement which has--in addition to a pleasant fat-like mouth feel despite a very low or no fat content--good color, good flavor impact from both buttery and salty flavors, a high water content without problems of flavor or microbiological stability, and a degree of fat-like melt without causing toast or other similar substrate to to which it is applied to become soggy due to moisture release.